Question

Janine is considering buying a water filter and a reusable water bottle rather than buying bottled water. Will doing so save her money?
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• How much water does Janine drink in a day? She normally drinks 6 bottles a day, each 16.9 ounces.
• How much does a bottle of water cost? She buys 24-packs of 16.9 ounce bottles for $3.19.
• How much does a reusable water bottle cost? About $10.
• How long does a reusable water bottle last? Basically forever (or until you lose it).
• How much does a water filter cost? How much water will they filter?
  • A faucet-mounted filter costs about $28 and includes one filter cartridge. Refill filters cost about $33 for a 3-pack. The box says each filter will filter up to 100 gallons (378 liters)
  • A water filter pitcher costs about $22 and includes one filter cartridge. Refill filters cost about $20 for a 4-pack. The box says each filter lasts for 40 gallons or 4 months
  • An under-sink filter costs $130 and includes one filter cartridge. Refill filters cost about $60 each. The filter lasts for 500 gallons.

Which option is cheapest over one year (365 days)?
The cheapest option saves her $______ over a year.
Give your answer to the nearest cent. Pro-rate the costs of additional filters (so if you only use part of a filter, only count the corresponding fraction of the filter cost).

Answer 1